This invention relates generally to injection syringes comprising a cylindrical barrel provided at its open rear end with a finger rest region where a finger rest is disposed. An inserted or permanently fitted cannula or a conical fitting for the subsequent fixing of a cannula is located at the forward end of the barrel. A plunger closes the open rear end of the barrel and is slidably displaceable by a ram.
Such injection syringes are used in medical practice for the administration of injectants subcutaneously, intramuscularly, intravenously or in other conventional ways.
Generally, these syringes are made of glass and sometimes or synthetic plastics. Their principal functional parts are the barrel which serves for the reception of the injectant in liquid or solid form, and the plunger which can be moved from the outside by the ram to displace the injectant through the outlet opening in the barrel neck or through a terminal fitting into the body by a cannula.
As is well understood such an injection syringe is manipulated with one hand and must therefore be provided with a surface for applying pressure with the thumb and with a finger rest for the index and middle fingers of the operator's hand.
This finger rest is a component which is either integrally formed with the barrel of the syringe or separate therefrom and adapted to be fitted over the end of the barrel and to be thus secured. In such a case the finger rest need not be made of glass like the barrel of the syringe, instead of which it may consist of a synthetic plastics or some other suitable material.
For ensuring that the separate finger rest is a firm fit, a known practice is to form a projecting ring on the end of the barrel of the syringe. However, the presence of such a projecting ring is open to the objection that conventional machines are unsuitable for producing and further working a syringe with a barrel of such a kind.
The attachment of a finger rest to the cylindrical barrel having a projecting ring requires special machines which significantly raises the cost of production.